[Asterisk-Dev] Answer Supervision for incoming calls in Asterisk

[Fernando Romo]

Dear Developers:

after search in Users, Devel am Google, i put the following scenario 
that need "answer supervision" for incoming calls and avoid invalid 
billing service for a customer:

Asterisk can identify the bits in a digital Line (in my case E1) and 
when the far side answer the call, asterisk open the sound channel, but 
i need a inverse schema.

I receive calls for a 1-900 number (pay per minute call) and need to 
play a message in place of the ringtones warning the customer the 
charges, if the client still in line i need to send a "answer 
supervision" bit to the carrier, then the customer start to charge the call.

The warning message say somethink like this: "This a pay per minute 
line, if you want to the service still in line after the tone and we 
charge your phone call, if not hangup now" when the beep sounds, i need 
to send the "answer supervision" and the carrier of the other side must 
start to measure the customer call.

Asterisk can handle this schema? with Answer app? if i put a "Playback" 
sound and the "answer" apps in  the dial plan is enough for this 
purposes? in my test the asterisk inmediate answer the line and send the 
"answer supervision" bits inmidiatly.

You have any idea about it?

Thanks in advanced..... El Pop